Questions on .ts and interlace/progressive

Discussion in 'General TV Discussions Forum' started by Monty Burns, Dec 19, 2006.

  1. Monty Burns

    Monty Burns
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    Hey-up guys,

    q1: .ts files, are they compressed at all? My mate seems to think they are but i'm not sure. He's claiming that they are not "true" hd and not how hd stuff will appear from a blueray player. I can understand they maybe encrypted but, even if they are compressed, would it make a diference to the quality we see now?

    q2: Now from my days of assembler programming and spanking gfx memory directly, interlacing was drawing, for example, every even row of pixels and then on the next refresh doing the odd rows. Basically, you would only draw half the screen on each refresh but to the naked eye (hopefully!) you should appear to get the full 1080. The same mate from question 1 said that 1080i stuff only infact uses 540 lines and its not how I think it works. Who's right?



    Thanks loads in advance for helping a very confused person. :D
     
  2. Monty Burns

    Monty Burns
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    Well, if the stickied post at the top of this is correct, then so am I! I'm not going completley mad. :rotfl:

    Anyone any ideas on Q1?
     
  3. TivoUK

    TivoUK
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    Q1 only - a .ts file is the raw transport stream data from the HD broadcast in the States (generally), so is not compressed. However, the bandwidth of HD broadcasts is not as high as HD DVD / Blu-Ray so in theory the .ts should look worse than a HD DVD / BR version of the same film, but a lot depends on how it was encoded etc. Saying that, I have both the .ts of the newest Kong and the HD DVD, the the HD DVD looks a bit better
     
  4. Caoimhghin

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    TS files are MPEG2-TS, where TS=Transport Stream, and is a broadcast standard for MPEG2. Being digital the quality of the stream will be determined by the bitrate. For it to be HD it must have a resolution of 720p or 1080p(i). So to answer your question it is a compressed standard.

    If you really want to know about it in detail then this link is a good place to start:

    http://erg.abdn.ac.uk/research/future-net/digital-video/mpeg2-trans.html
     
  5. Monty Burns

    Monty Burns
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    Ahh ok. So the BR/HD DVD stuff contains the Elementary Stream then (uncompressed) and .ts has the compressed version? Does that mean that we will see a diference if they were placed side by side on identical kit?
     
  6. Caoimhghin

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    Digitally rendered video/audio is normally by definition compressed irrespective of its container, the amount of compression is dictated by its bitrate (the amount of data being decoded per second). Consequently the higher the bitrate (throughput) the better the quality and larger the file. Obviously, there will come a point where it is difficult to discern the difference between a digitally compressed stream and an analogous uncompressed stream. Video and audio quality is subjective to the individual, that's why with formats like DIVX-HD the perceived quality to file size ratio is considered so good.

    At the end of the day the perceived quality relies on so many things, the efficiency of the codec used, its encoder and decoder, and just as importantly the hardware used in this process.
     
  7. Monty Burns

    Monty Burns
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    gotch ya :thumbsup:

    Thanks very much :)
     
  8. arfster

    arfster
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    Uncompressed 1080i = something like 500 Gbytes/hour. Not terribly practical :)
     
  9. Mr.D

    Mr.D
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    whatever way you slice it the material is going to be displayed progressively ( as frames) whether it decodes to an interlaced video sequence or progressive.

    Assuming its interlaced and assuming the field arrangement hasn't been messed up( most broadcast .ts is either 1080i or 720p) it all boils down to how well your display chain can deinterlace it. If its rubbish it will do a "bob" deinterlace and resize every 1920x540 field to full height 1920x1080 and display each field as a frame.

    If its got decent deinterlacing it will detect the 3:2 pulldown sequence , inverse telecine it (correctly reinterlaced thwe fields to real frames and lose the repeat fields) and introduce frame repeats to match to your refresh rate ( a multiple of 24 would be ideal but if it doesn't deinterlace properly 60Hz will likely give better results).
     

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